Ouyang Shixi

Molten salt synthesis of Ba(Mg1/3 Nb2/3)O3 powder

The single-phase Ba(Mg1/3 Nb2/3)O3 (BMN) powder was successfully prepared by the KCl molten salt synthesis (MSS) method. The temperature for single-phase BMN powders by MSS was about 400°C lower than that by the solid-phase method. The average particle size (APS) was about 0.91 μm at 900°C and increased with increasing synthesis temperature. Based on the APS, the activation energy for particle growth in the MSS, whose value was 64.1 kJmol-1, was attained. The sinterability of the powder prepared by MSS method was better than that prepared by solid-phase method.The single-phase Ba(Mg1/3 Nb2/3)O3 (BMN) powder was successfully prepared by the KCl molten salt synthesis (MSS) method. The temperature for single-phase BMN powders by MSS was about 400°C lower than that by the solid-phase method. The average particle size (APS) was about 0.91 μm at 900°C and increased with increasing synthesis temperature. Based on the APS, the activation energy for particle growth in the MSS, whose value was 64.1 kJmol-1, was attained. The sinterability of the powder prepared by MSS method was better than that prepared by solid-phase method.

Synthesis and performance of LiMnO2 as cathodes for Li-ion batteries

Two structure types of LiMnO2 were synthesized by sol-gel method and ion-exchange method respectively. The results indicate that orthorhombic phase LiMnO2 is more stable than layered LiMnO2, o-LiMnO2 can be synthesized directly by sol-gel methods followed by heat-treated in argon, but layered LiMnO2 was obtained only by indirect methods such as ion-exchange method. In this paper, we first synthesized layered NaMnO2 by the sol-gel method, and then obtained layered LiMnO2 by the ion-exchange method. The phase, constitution, chemical composition, and images of the products were tested by XRD, AAS (atomic absorption spectroscopy) and SEM. The electrochemical performances of the two structural types of LiMnO2 are obviously different during the initial few cycles, but later they both have a good capacity-retaining ability. The capacity of layered structure LiMnO2 is higher than that of o-LiMnO2.

Synthesis and X-ray powder diffraction characterization of a new niobate crystal NaBa2Li0.6Nb4.8Zn0.2O15

A new niobate compound was synthesized for the first time in Na2O-BaO-Li2O-ZnO-Nb2O5system by solid state reaction. The new compound was studied by X-ray diffraction, electron probe, X-ray microanalysis, chemical analysis and SEM. The result of X-ray powder diffraction shows that NaBa2Li0.6Nb4.8Zn0.2O15belongs to orthorhombic tungsten bronze structure, with space group Pba2(32)and lattice parameters a = 12.6115(2)Å, b=12.4981(2)Å, C = 3.9479(3)Å.The X-ray powder diffraction lines of the compound were well indexed.

Synthesis and Microstructure of Partly-oriented Bismuth Layer Structure Ferroelectrics Ceramics SrBi4Ti4O15

SrBi4Ti4O15 powder was synthesized by conventional solid state synthesis (CS) and molten salt synthesis (MSS). MSS method can synthesize plate-like SrBi4Ti4O15 at lower temperature (900°C) than CS method. Plate-like form becomes more distinct when the synthesis temperature increases. This would help cause the grain orientation of the ceramics after sintering. The sintered samples of MSS had grain orientation at (0,0,10) plane. The degree of (0,0,10) grain orientation F was 62.1%. Hot pressing made (0,0,10) grain orientation more distinct (F=85.7%). The microstructures of the sintered samples were detected by SEM. Due to the grain orientation, the density of samples fabricated by MSS was lower than that of prepared by CS.

Synthesis and Field Emission of ZnO Nanostructures on CuO Catalyzed Porous Silicon Substrate

Mass production of ZnO nanobelts and hexagonal nanorods has been successfully synthesized on CuO catalyzed porous silicon (PS) using a simple vapour–solid (VS) growth method. A comparison of their morphologies is investigated by scanning electron microscopy (SEM). The transmission electron microscopy (TEM) confirms that ZnO nanobelts and nanorods are single crystalline with the growth direction of (010) and (0001), respectively. Field emission tests indicate that the ZnO nanostructures on porous silicon have low turn-on field of about 3.6 V/μm (at 1.0 μA/cm2) and the threshold field of about 8.3 V/μm (at 1.0 mA/cm2), high emission site density (ESD) of approximately 104 cm−2.

The Dielectric Properties and Structure of Ni-Doped (0.8-x) PMT-0.2PZ-xPT Ternary System Near Morphotropic Phase Boundary

Morphotropic phase boundary (MPB) of (0.8-x)PMT-xPbTiO3(PT)-0.2PbZrO3(PZ) ternary system (x = 0.4) was studied by X-ray diffraction (XRD). It shows that by comparing with 0.4PMT-0.2PZ-0.4PT sample, after doping with Ni, c/a remains almost same (about1.009), while both c and a decrease indicating that lattice shrinks. Content of the tetragonal phase TP% of Ni-doped samples increase up to 81.1% when the doping limit of the nickel is reached (y = 0.05), and the dielectric constant ϵ was found to increase up to 4570 when y = 0.05 and the Curie temperatures of doping samples were found to decrease from 175°C to 157°C.

Effect of B2O3 on the Structure and Photoluminescence Properties of Sol-gel Glass Doped with Terbium Organic Complex

Both silica and boron-silica glass materials doped with terbium organic complex were prepared by in situ sol-gel method respectively. XRD and SEM measurements were performed to verify the non-crystalline structure of the glass. The influence of the glass contents on the structure of the glass and the energy level of the doped Tb (III) ions was analyzed by the emission spectra and IR spectra. The effect of B2O3 on the photoluminescence properties of rare earth organic complex in silica-based glass was investigated. The IR spectra indicate that the in situ synthesized rare earth complex molecule was confined to the micropores of the host and the vibration of the ligands was frozen. When B2O3 was added into the silica host gel, B2O3 had little influence on the noncrystalline structure of the glass, and BO3 triangle, which had a layer structure different from the silica framework, could form. So the silica network became more inhomogenous, and the luminescence of terbium complexes was quenched with the increase of the B2O3 amount.

Synthesis and Characteristic of a New Niobate: Ba5NaCr0.5Nb9.5O30

A new niobate crystal was synthesized for the first time in BaO−NaO−Cr2O3−Nb2O3, ystem by the solid state reaction and the flux method. The new compound was studied by X-ray diffraction, electron probe, X-ray microanalysis, chemical analysis and SEM. The result of X-ray powder diffraction show that Ba5NaCr0.5 Nb9.5O30 belongs to the tetragonal tungsten bronze structure, with space group P4 bm(100) and lattice parameters a=b=12.4450(2)A, c=3.9931(2)A and Z=1. The X-ray powder diffraction lines of the compound were well indexed.

Aqueous Tape Casting Process with Styrene-acrylic Latex Binder

A commercial styrene-acrylic latex binder has been investigated as a good binder for aqueous Al2O3 suspensions tape-casting process. This paper focuses on the forming film mechanism of latex binder, the rheological behaviors of the suspensions, physical properties of green tapes and drying process of aqueous slurries with latex binder system. The drying process of the alumina suspensions is shown to follow a two-stage mechanism (the first stage: evoporation controlled process; and the second stage: diffusion controlled process). During the drying stage of the suspensions, the compressive force presses the latex particles and makes them be distorted, which results in cross-linking structure in contacted latex particles of the solidified tapes. A smooth-surface and high-strength green tape was fabricated by aqueous tape casting with latex binder system. The results from the SEM images of the crossing section microstructure of green tapes show that the latex is a very suitable binder for aqueous tape casting.

Preparation of poly (ethylene oxide) (PEO) modified tungsten oxide hybrid filmsvia sol-gel processing

Poly (ethylene axide) (PEO) modified WO3 thin films were prepared on glass substrates with special temperature. The sol-gel transition proess was investigated by using DTA-TG, SEM and XRD. The electrochemical characteristic of the films was studied by cyclic voltmmetry measurement. The results show that PEO has heavy effects on the crystallization of WO3 during structure evolution because of the interaction between PEO and WO3. It increases the crystallization temperature of the gels and thus improves the electrochemical properties and cyclic life of WO3 film as electrochromic materials.